Bars, eggs, etc. There's a variety of nutritional bars that are high protein and low carb. Walnuts, almonds and peanuts provide some "healthy fat" and decent amounts of protein with very few carbs. String cheese made with skim milk is another good option. Peanut butter or almond butter has a decent amount of protein and is low carb. Anything predominately with eggs/egg whites would meet your criteria.